Convenient partial purification of polyphenol oxidase from apple skin by cationic reversed micellar extraction

Polyphenol oxidase (PPO) was selectively extracted from reconstituted freeze-dried apple skin using reverse micelles formed by a cationic surfactant, dodecyl trimethyl ammonium bromide (DTAB). An optimum forward extraction was achieved with sodium phosphate buffer (pH 6, 100 mM, no added KCl) and an organic phase (isooctane:hexanol at a ratio of 5:1) containing 100 mM DTAB. The solubilised PPO was efficiently recovered by a stripping solution (pH 6, 1 M KCl) containing 10% ethanol. Under the optimised conditions, the purification fold and recovered activity of PPO were 12.6% and 71%, respectively. This purification fold and recovery were maintained when the extraction volume increased from 10–200 ml. Overall, reversed micellar extraction can be used as an efficient first step for the purification of PPO from apple skin.